1. Field of the Invention
The present invention relates to a method of making the elements of a continuously variable transmission belt. The elements of a continuously variable transmission belt are metal pieces that constitute a Van Dome type belt used in a continuously variable transmission used on automobiles.
2. Description of the Related Art
The prior art in this field is exemplified in Unexamined Publication of Patent Application (A) 2001-246428. As shown in FIG. 3 of said publication, element 1 is produced by punching it out from plate 12. Plate 12 has corners 14 and the central part in a cross section is thick, while the thickness reduces outward from each corner 14 in a tapered shape. A pair of elements 1a and 1b is aligned by said tapered shape and is punched out by means of the fine blanking method.
The problems with this prior art are: firstly, plate 12 is expensive to manufacture; and secondly, it is difficult to obtain identical elements from tapered plate 12. In other words, it is difficult to control the accuracies of the dimensions (primarily the thickness) and the shape of the punched out elements. The first problem can be easily understood from the fact that it is more expensive to produce a tapered plate accurately than to produce a flat plate from the standpoint of facility requirements and complexity of the machining process. The second problem can also be easily understood from the fact that the punching of a tapered plate causes delicate changes in the thickness in various parts of the plate, so that plates with uniform dimensions and shapes cannot be obtained without determining the locations of those parts in high accuracy.
3. Problems to be Solved by the Invention
The present invention intends to provide a method of making the elements of a continuously variable transmission belt of high accuracy using a relatively inexpensive plate blank.